Several methods for preparing fluorinated olefins are known. Likewise, various reactors for conducting catalytic reactions are known. The following references are cited as non-exclusive examples. These documents are hereby incorporated herein by reference:
U.S. Pat. No. 4,876,405 discloses a process for preparing fluoroethylenes and chlorofluoro-ethylenes from chlorofluoroethanes.
U.S. Pat. No. 5,118,888 discloses a process for the preparation of 1,2-difluoro-ethylene and 1-chloro-1,2-difluoroethylene.
U.S. Pat. No. 5,396,000 discloses a process for producing CF3CHFCH2F using vapor phase catalytic dehydrohalogenation to produce CF3CF═CHF and HF, followed by vapor phase catalytic hydrogenation of CF3CF═CHF in the presence of HF.
U.S. Pat. No. 5,679,875 discloses methods for manufacturing 1,1,1,2,3-pentafluoropropene (HFO-1225ye) and 1,1,1,2,3-pentafluoropropane (HFC-245eb).
U.S. Pat. No. 6,031,141 discloses a catalytic process using chromium-containing catalysts for the dehydrofluorination of hydrofluorocarbons to fluoroolefins.
U.S. Pat. No. 6,548,719 discloses a process for producing fluoroolefins by dehydrohalogenating a hydrofluorocarbon in the presence of a phase transfer catalyst.
U.S. Publication No. 2006/0106263 discloses the production and purification of hydrofluoroolefin compounds.
U.S. Publication No. 2007/0179324 discloses processes for the production of fluorinated olefins, particularly fluorinated propenes such as the HFO-1234 series.
U.S. Publication No. 2007/0197842 discloses processes for the production of fluorinated olefins including 2,3,3,3-tetrafluoro-2-propene (HFO-1234yf).
U.S. Publication No. 2008/0023175 discloses a method for varying the temperature in a tube bundle reactor for catalytic gas phase reactions.
U.S. Publication No. 2009/0030245 discloses a method for preparing 2,3,3,3-tetrafluoropropene comprising contacting a reactant comprising CCl2=CFCH2Cl with a fluorinating agent, such as HF, under conditions effective to produce a reaction product comprising CF3CF═CH2.
EP Publication No. 1586370 discloses a reactor useful for conducting catalytic gas phase reactions.
PCT Publication No. WO1998/33755 discloses a catalytic process for the dehydrofluorination of hexafluoropropanes to pentafluoropropenes.
PCT Publication No. WO2008/030440 discloses a catalytic process for the preparation of 2,3,3,3-tetrafluoropropene.
PCT Publication No. WO2008/030444 discloses a catalytic process for the preparation of 1,2,3,3,3-pentafluoropropene.
PCT Publication No. WO2008/054778 discloses a catalytic process for the preparation of 2,3,3,3-tetrafluoropropene, a process for producing 1-chloro-2,2,3,3,3-pentafluoropropane and azeotropic compositions of 1-chloro-2,3,3,3-tetrafluoropropene with HF.
Applicants have discovered that the processes of the type described above have disadvantages and/or are not as effective and/or economical as would be practically necessary for large scale commercial production. For example, applicants have come to appreciate that it is generally not possible, by following the teachings of the above references alone, to achieve a process having at once a high degree of ultimate conversion and a high degree of selectivity to the desired fluorinated olefin.
Hydrogenation reactions involving fluoro-olefins are typically highly exothermic. If the heat generated from the reaction is not adequately managed, the high temperatures in the reactor may cause excess hydrogenation, or other side product formation, resulting in reduced yields of the desired product. Therefore, it is necessary to control the reaction temperature.
One method traditionally employed in hydrogenation processes is a large recycle of a cooled portion of the reaction product to cause heat transfer in what's commonly referred to as the trickle bed reactor (a fixed bed reactor packed with catalyst). Recycle of reaction product may not always be suitable especially when the reaction product is susceptible to hydrogenation.
For example, in the hydrogenation of HFC-1225ye (1,2,3,3,3-pentafluoropropene), HFC-236ea (1,1,1,2,3,3-hexafluoropropane) is the desired product but HFC-254 (tetrafluoropropane) is an over-hydrogenation side product that is also observed). Similarly, when the latent heat of the reaction product is low, as in fluorocarbons, processing requires large amounts of recycling, thus making the process less economical. Hence, it is desirable to provide an improved process for the hydrogenation of fluoro-olefins in terms of economics, temperature control and overall safety.